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Large‐scale intertidal polygonal features of the Abu Dhabi coastline
Author(s) -
LOKIER STEPHEN,
STEUBER THOMAS
Publication year - 2009
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/j.1365-3091.2008.00988.x
Subject(s) - geology , sedimentary depositional environment , intertidal zone , carbonate , cementation (geology) , sedimentary structures , sedimentary rock , sediment , sedimentology , geochemistry , geomorphology , abu dhabi , paleontology , oceanography , cement , materials science , archaeology , metropolitan area , structural basin , metallurgy , history , medicine , pathology
This study provides the first quantitative description of modern giant polygons. These large‐scale, up to 166 m diameter, sedimentological features are described here in detail from the intertidal zone of the Arabian Gulf near Abu Dhabi. These features form by the displacive carbonate cementation of carbonate sand below a 3 to 5 cm thick cover of unconsolidated sediment. The oxygen isotopic composition of cements is consistent with precipitation from evaporated sea water. Cementation proceeds via a poorly consolidated layer that grades downward into an 8 to 14 cm thick, well‐cemented grainstone. The margins of this expanding hardground form the overlapping borders of the polygons. Tepee structures at the borders of polygons are only occasionally preserved, as supporting sediment is removed by strong tidal currents and high‐energy events, such as storms, that erode the unsupported tepees. These observations have clear implications for the use of tepees in the interpretation of ancient polygons and their associated environments. When preserved in the sedimentary record, tepee structures are interpreted to indicate lower energy depositional environments than that observed in this study.